Electric switch



Dec. 31', 1929. Q APPELBERG 1,741,600

ELECTRIC SWITCH Original Filed Sept. 21, 1921 Patented Dec. 31, 1929 UNITED STATES PATENT OFFICE 31mm REGULATOR, or s'rocK oLM,

swnnnn swnnrln, A JOINT-STOCK COMPANY or ELECTRIC SWITCH Original appiication 'filed September 2 1e21,'seria1' 1105502301, aim in- Sweden September 30,3920.

. Divided and thisapplication filed Mai'qh 21, 1923; Serial no. 626,674.

This, invention relates to electric switches and. more particularly to periodical switches.

The damaging effect of the break sparks on the switch contacts is a great disadvantage, especially. in periodical switches, in which the breaking of the current occurs at short intervals during long periods, and limits the use of such switches.

In accordance with the present invention the break sparks are eliminated to an essential degree by making the contacts of tungsten, molybdenum, tantalumbr other refractory metal comparable therewith and .disposing them in a receptacle, which is either evacuated'or filled with an inert gas or gaseous mixture ,at suitable pressure. Prefer ably, a highly evacuated receptacle is used paratus and the like.

but receptacles filled with gas such as nitrogen, argon, neon, hydrogen or the like can also be used. i

The favourable result obtained'by the present inventio n in regard to the durability of the contacts and their capability of breaking even' comparatively strong currents is mainly attributed tothe combined effect of {the vacuum and, the high evaporatin temperature of the contact metal, where y the arcing is-rendered more diflicult and thus the .breakingtakes place quicker although the contacts may have a slow movement. This last mentioned quality renders the invention especially suitable for thermostatic switches, but it can also be used in otherlkinds of breakers.

' On account of the great durability of the breaking contacts the device is particularl suitable for periodical switches'o'f every kin forinstance limiting switches, switches for flash lights, and self-interrupting devices,

especiallythermostatic ones for regulating the supply. ot current toelectric heating ap- One embodiment of the invention is shown in the accompanying drawing'to which reference will now be made.

The wo contacts 1,

ated or filled with aninert gas, one of said tongues, 4, consisting of a stifl plate and the 2 are arranged at the, free endsof two contact tongues 3, 4; fused .in one end of atube or bulb, which is evacuother consisting of two metallic laminae soldered together, said laminae having different co-efiicients of expansion and forminga so called bi-metal or thermostat-metalf.

On an increase in the surrounding temperae ture the thermostat 3 bends outwards from ceeds a certain temperature and allowing only such a quantity of energy to-pass as is'suificient to maintain said temperature.

When used as a current limiting device the bimetallic tongue 3 may be provided with a heating coil 6. Said heatingeoil is preferably inserted in series w ith the main electric circuit.

Owing to its small dimensionsa device of this character is easily applicable to current consuming apparatus as generally used and wherein the strength of current shall not exceed a certain limit. For example, such current supply limiting devices may be arranged in lamp holders, the consumption being limitedto lamps of a certain maxi mum of luminous intensity.

What Iclaim as new and desire to secure by Letters Patent of the United States of America is V 1. 'A'thermostatlc switch sealed in an evacuated receptacle and consisting of a oi-metallic stem, a switch member co-operating therewith, a heating winding on .said bi metallic stem, break contacts consisting. of refractory metal, and. outer terminals connected with said bi-metallic stem and said switch member. v v

2. A current limiting device for lightinstallations, consisting of, a thermostatic switch having a heating windifigin'cluded" in the lamp circuit, saidswitch consisting of a bi-metallic stem sealed in an eyacuated receptac1e,and provided with contacts consisting of tungsten.

3; A current limiting device for light installations consisting of a thermostatic switch having a heating Winding included in the lamp circuit, said switch consisting of a bimetallic stem sealed an evacuated receptacle, and provided with contacts consisting of a refractory metal,

In testimony whereof I affix my signature.

AXEL OSVALD APPELBERG. 

